which sororities are toughest to get a bid from?

It really all depends on the qualities you bring to the table. For instance, I was a PNM from a private school in Mobile with a 3.75 gpa, pre-med major, average to above average looks (I look young for my age), and had a lot of service-based ECs. PM and AGD dropped me after the first round. XO dropped me after the second round (as a legacy), I dropped Kappa after the 3rd round, and I had AXO, KD, and DDD for pref. All houses are hard to get into depending on your specific situation and the conversations you have with girls in the house.

DDD, KD, KKG,AGD- if you aren't from the south. I know a few people that have done it

Lastly these depend chi o, A chi o and pm
Pretty much all the old row houses are hard to get bids from even if you're a legacy